Suspension strut top mount

ABSTRACT

A suspension strut top mount having a bearing connection onto a vehicle body and a spring retainer for a vehicle support. The spring retainer is set obliquely relative to a central axis of a suspension strut. The suspension strut top mount further has an obliquely set bearing arranged between the bearing connection and the spring retainer and has a bearing input part, which is associated with the bearing connection, and a bearing output part, which is associated with the spring retainer. A stop buffer, which is arranged concentrically to the central axis of the suspension strut, comes into contact on a cylinder-end surface of the suspension strut in a defined spring compression position. The stop buffer has an effective connection to the bearing output part of the bearing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a suspension strut top mount for use in avehicle body.

2. Description of the Related Art

U.S. 2003/0006574 A1 discloses a suspension strut top mount forconnection onto a vehicle body which has a bearing between a springretainer and a bearing connection to the vehicle body. A second springretainer is fastened at the cylinder end, the cylinder synchronouslyexecuting a pivoting motion during a steering motion of a vehicle wheel.The pivoting motion is transferred to the bearing-end spring retainer bya vehicle support spring, which is restrained between the two springretainers. The bearing prevents restraint from occurring within thebearing, which reduces comfort, on the one hand, and has a negativeeffect on the life of the suspension strut top mount on the other.

The central axes of the bearing-end spring retainer and the bearingextend identically with the steering axis of the vehicle wheel. Thismeasure is intended to prevent disturbing steering torques, which cancause an out-of-track motion of the vehicle.

The suspension strut top mount forming the generic type also has a stopbuffer which, relative to the force path within the suspension strut topmount, is axially supported parallel to the bearing. In the case ofsuperimposed spring compression and steering motions, a condition canoccur where the stop buffer lands on a cylinder-end surface of thesuspension strut and blocks the pivoting motion capability of thebearing on the spring retainer.

So that this problem does not occur, DE 83 11 927 U1 discloses that thestop buffer can execute a twisting motion relative to the cylinder bymeans of a second bearing. Such a second bearing, however, representssubstantial cost and installation space expenditure.

SUMMARY OF THE INVENTION

The object of the present invention is to realize a vibration damperwhich, in the case of an obliquely set bearing within a suspension struttop mount, solves the blocking problem, in association with a stopbuffer, known from the prior art.

According to the invention, the object is achieved by the stop buffer'shaving an effective connection to the bearing output part of thebearing.

The major advantage of the invention consists in the fact that the stopbuffer can execute a relative motion in the peripheral direction withrespect to the suspension strut without a blockage and restraintsituation occurring within the suspension strut top mount. The technicalrequirement is also very simple because, with only one bearing, thecomplete suspension strut top mount, including the spring retainer, isrotationally decoupled from the cylinder of the suspension strut.

In a further advantageous embodiment, the central axis of the obliquelyset bearing and a steering axis of the suspension strut are aligned soas to be at least approximately coincident. Comprehensive tests haveshown that, despite the angular setting between the stop buffer and thesteering axis, about which the suspension strut pivots during a steeringmotion, no clamping forces or friction forces occur between the stopbuffer and a piston rod of the suspension strut.

Provision is made for the spring retainer to have an outer surface onwhich the stop buffer is radially supported. For this purpose, thespring retainer has a sleeve section, which extends concentrically withthe central axis of the suspension strut.

In addition, the spring retainer has a retention surface for a tubularprotective element enveloping the stop buffer. As a consequence, notorsional loads occur within the protective element either so that theprotective element can be connected at one end to the cylinder of thesuspension strut.

The bearing output part has a support surface for the axial support ofthe stop buffer. To avoid transverse forces, the support surface isaligned at right angles to a central axis of the suspension strut.

With a view to a simple assembly procedure, the spring retainer and thebearing output part form a press connection by means of axiallyextending clamping surfaces. The spring retainer and the bearing outputpart can form a structural unit which can be pre-assembled. Thestructural unit can be produced independently of a specified cycle timewithin an assembly procedure of the overall suspension strut.

The spring retainer should preferably consist of a plastic. So that,nevertheless, even very large forces can be transferred to the bearingoutput part, a reinforcement sleeve for the spring retainer is arrangedbetween the stop buffer and the spring retainer.

The reinforcement sleeve has an annular end, which is supported on thebearing output part. This measure additionally stiffens thereinforcement sleeve and offers the possibility of employing arelatively thin-walled bearing output part.

To axially secure the stop buffer to the suspension strut top mount, asnap connection is present between the reinforcement sleeve and the stopbuffer.

The reinforcement sleeve has at least angled edge sections, possiblyalso a completely circumferential edge, which are axially supported onthe spring retainer.

The at least angled edge sections of the reinforcement sleeve provide afurther retention surface for the tubular protective element. As aconsequence, two alternately effective retention surfaces are presentfor the tubular protective element, so that a clearance-free fasteningis possible between the protective element and the suspension strut topmount.

Other objects and features of the present invention will become apparentfrom the following detailed description considered in conjunction withthe accompanying drawings. It is to be understood, however, that thedrawings are designed solely for purposes of illustration and not as adefinition of the limits of the invention, for which reference should bemade to the appended claims. It should be further understood that thedrawings are not necessarily drawn to scale and that, unless otherwiseindicated, they are merely intended to conceptually illustrate thestructures and procedures described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail using the followingdescription of the figure, which illustrates an axial sectional view ofthe invention suspension strut.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

The figure shows a suspension strut top mount 1 for a suspension strut3, of which only an upper partial region is shown. The suspension struttop mount has a bearing connection 5 to a vehicle body, which is notshown. By means of its cup-shaped three-dimensional shape, the bearingconnection 5 accommodates an elastomer body 7, which at least partiallyencloses a connecting ring 9 on the outside, the connecting ring havingan axial and torsion-proof connection to a piston rod 11 of thesuspension strut.

On the outside, the bearing connection has a further elastomer body 13,on which a bearing 15 is supported axially and radially. The bearing 15is aligned obliquely with its central axis at least approximatelycoincident with a steering axis 16. Compensation for centrifugal forceshas to be achieved by the obliquely set bearing 15 without the bearingitself being critically loaded. The steering axis 16 encloses an angle αwith a central axis 19 of the suspension strut 3. The bearing 15comprises a bearing input part 15 a and a bearing output part 15 b,which parts can execute a rotational motion relative to one another. Forthe invention, it is unimportant whether a rolling contact bearing or asliding bearing is used. A spring retainer 17 for a vehicle supportspring 21, which is in contact at its other end with a cylinder-endspring retainer 23, is supported on the bearing output part 15 b. Thecentral axis of the vehicle support spring is also at leastapproximately aligned identically to the steering axis 16. The springretainer 17, which is preferably manufactured from a plastic, has asleeve section 25 so that, between the spring retainer 17 and an offsetregion of the bearing output part 15 b clamping surfaces 27, 29, a pressconnection is present between the bearing output part 15 b and thespring retainer 17.

A stop buffer 31 is arranged concentrically with the central axis 19 ofthe suspension strut 3, which stop buffer 31 comes into contact, from adefined spring compression position of the piston rod 11 in a cylinder33, with a cylinder-end surface 35 of the suspension strut which, inthis case, is formed by an additional cap 37. The stop buffer 31 haseffective connection with the bearing output part 15 b of the bearing15, so that these two parts move synchronously, axially and in theperipheral direction.

The spring retainer 17, in particular the sleeve section 25, has asurface 39 on which the stop buffer 31 is radially supported. A supportsurface 41 of the bearing output part 15 b, which support surface 41 isaligned at right angles to the central axis 19 of the suspension strut,provides axial support. The internal diameter of the stop buffer 31 andthe piston rod 11 form a free annular space 42 in order to avoid arubbing contact between the piston rod 11 and the stop buffer 31.

A reinforcement sleeve 43 is arranged between the stop buffer 31 and thespring retainer 17. This reinforcement sleeve has an annular end, 45,which is axially supported on the bearing output part 15 b. Thereinforcement sleeve 43 and the stop buffer 31 form a snap connection 47which, for example, contains radially inwardly directed beads of thereinforcement sleeve 43, which beads engage in a groove of the stopbuffer.

The piston rod 11 and the stop buffer 31 are enveloped by a tubularprotective element 49, in this exemplary embodiment an axially elasticbellows, the protective element 49 being axially supported at one end ona retention surface 51 of the spring retainer 17. The reinforcementsleeve 43 has at least angled edge sections 53, possibly a completelycircumferential edge, which edge is supported at the end on the springretainer 17, this edge providing a further retention surface 55 for thetubular protective element 49.

During straight-line travel and a small to average spring compressionmovement of the piston rod 11 toward the cylinder 33 of the suspensionstrut, there is neither a bearing motion nor a contact of the stopbuffer 31 with the cylinder-end surface 35.

A steering motion, even in association with a spring-compression motionof a wheel, which is not shown, about the steering axis 16 leads to atwisting motion within the bearing 15 and, as a consequence, to awobbling motion of the stop buffer relative to a hypothetical verticalreference line, for example the central axis 19. At the same time,however, the suspension strut 3 also moves three-dimensionally about thesteering axis 16, so that the annular space 42 prevents a rubbingcontact between the stop buffer 31 and the piston rod 11 despite therelative motion of the stop buffer 31 relative to the piston rod 11.

Thus, while there have shown and described and pointed out fundamentalnovel features of the invention as applied to a preferred embodimentthereof, it will be understood that various omissions and substitutionsand changes in the form and details of the devices illustrated, and intheir operation, may be made by those skilled in the art withoutdeparting from the spirit of the invention. For example, it is expresslyintended that all combinations of those elements and/or method stepswhich perform substantially the same function in substantially the sameway to achieve the same results are within the scope of the invention.Moreover, it should be recognized that structures and/or elements and/ormethod steps shown and/or described in connection with any disclosedform or embodiment of the invention may be incorporated in any otherdisclosed or described or suggested form or embodiment as a generalmatter of design choice. It is the intention, therefore, to be limitedonly as indicated by the scope of the claims appended hereto.

1. A suspension strut top mount for connection onto a vehicle body,comprising: a bearing connection coupled to the vehicle body; a strutassembly extending along an axis and comprising a cylinder, wherein thecylinder and the bearing connection are operative to axially displacerelative to one another in response to applying an external force, thecylinder having an end surface opposing to and axially spaced from thebearing connection; a bearing mounted to the strut assembly obliquelyrelative to the axis, the bearing comprising an input part coupled tothe bearing connection and an output part; a spring retainer seatedagainst the output part of the bearing obliquely relative to the axis; avehicle spring supported by the spring retainer and spaced radiallyoutwards from the strut assembly, the vehicle spring being compressibleto a predetermined position in response to the external force; and astop buffer positioned between the vehicle spring and the strutassembly, the stop buffer being operatively connected to the output partof the bearing and displaceable therewith towards the cylinder inresponse to the external force so that the stop buffer abuts thecylinder end surface upon compressing the vehicle spring to thepredetermined position.
 2. The suspension strut top mount of claim 1,wherein the strut assembly has a steering axis extending transversely tothe axis, the bearing being centered about a bearing axis substantiallyaligned with the steering axis.
 3. The suspension strut top mount ofclaim 1, wherein the spring retainer has an axially extending surfacejuxtaposed with and radially supporting the stop buffer.
 4. Thesuspension strut top mount of claim 3 further comprising an axiallyextending tubular protective sleeve surrounding the stop buffer, thespring retainer having a retention surface configured to support one ofopposite axial ends of the tubular protective sleeve.
 5. The suspensionstrut top mount of claim 1, wherein the bearing output part has aradially extending support surface axially supporting one of oppositeaxial ends of the stop buffer.
 6. The suspension strut top mount ofclaim 5, wherein the support surface extends perpendicular to the axisof the strut assembly.
 7. The suspension strut top mount of claim 1,wherein the spring retainer and the bearing output part of the bearinghave axially juxtaposed surfaces pressing against one another so as tocouple the spring retainer and the bearing output part to one another.8. The suspension strut top mount of claim 1 further comprising areinforcement sleeve extending axially between the spring retainer andthe stop buffer and configured to support the spring retainer.
 9. Thesuspension strut top mount of claim 8, wherein the reinforcement sleevehas an annular end extending radially inwards towards the strut assemblyand supported on the bearing output part.
 10. The suspension strut topmount of claim 8 further comprising a snap connection unit mountedbetween the reinforcement sleeve and the stop buffer.
 11. The suspensionstrut top mount of claim 8, wherein the reinforcement sleeve has anangled edge section extending radially outwards from the stop buffer andaxially supported on the spring retainer.
 12. The suspension strut topmount of claim 11 further comprising a tubular protective elementextending axially from the angled edge section and supported thereon.13. The suspension strut top mount of claim 10, wherein the angled edgesection comprises a circumferentially continuous angled section or aplurality of circumferentially spaced apart angled subsections.